Latency reduction for transitions between active state and sleep state of an integrated circuit

Abstract

An apparatus and method for efficient power management of multiple integrated circuits. In various implementations, a computing system includes an integrated circuit with a security processor. The security processor determines the integrated circuit transitions to an active state from a sleep state that is not intended to maintain configuration information to return to the active state without restarting an operating system. In the sleep state, multiple components of the integrated circuit have a power supply reference level turned off, which provides low power consumption for the integrated circuit. The security processor performs the bootup operation using information stored in persistent on-chip memory. By not using information stored in off-chip memory, the security processor reduces the latency of the transition. The persistent on-chip memory utilizes synchronous random-access memory that receives a standby power supply reference level that continually supplies a voltage magnitude by not being turned off.

What is claimed is: 
     
       1. A security processor comprising:
 circuitry, wherein responsive to a first condition that indicates initialization of at least a first client of a plurality of clients of an integrated circuit, the circuitry is configured to:
 initialize the first client using configuration information stored in a persistent on-chip memory that is accessible by the circuitry and inaccessible by the plurality of clients, responsive to an indication that the persistent on-chip memory stores valid information. 
 
 
     
     
       2. The security processor as recited in  claim 1 , wherein the first condition comprises an indication of a transition of the integrated circuit from a sleep state to an active state. 
     
     
       3. The security processor as recited in  claim 1 , wherein the circuitry is further configured to perform a bootup operation using boot firmware stored in the persistent on-chip memory. 
     
     
       4. The security processor as recited in  claim 3 , wherein the circuitry is further configured to:
 retrieve the boot firmware from an off-chip memory; 
 store a copy of the boot firmware in the persistent on-chip memory; and 
 update a flag to indicate that the persistent on-chip memory stores valid information. 
 
     
     
       5. The security processor as recited in  claim 1 , wherein the circuitry is further configured to:
 retrieve data including the configuration information from an off-chip memory; and 
 store a first subset of the data in the persistent on-chip memory. 
 
     
     
       6. The security processor as recited in  claim 1 , wherein responsive to a second condition that indicates an update procedure, the circuitry is further configured to invalidate contents of a persistent on-chip memory. 
     
     
       7. The security processor as recited in  claim 1 , wherein the circuitry is further configured to:
 perform authentication of update information corresponding to boot firmware and configuration information retrieved from an off-chip memory; and 
 store a subset of the update information in the persistent on-chip memory. 
 
     
     
       8. A method, comprising:
 processing tasks by a plurality of clients of an integrated circuit; and 
 responsive to a first condition that indicates initialization of at least a first client of the plurality of clients:
 initializing, by circuitry, the first client using configuration information stored in a persistent on-chip memory that is accessible by the circuitry and inaccessible by the plurality of clients, responsive to an indication that the persistent on-chip memory stores valid information. 
 
 
     
     
       9. The method as recited in  claim 8 , wherein the first condition comprises an indication of a transition of the integrated circuit from a sleep state to an active state. 
     
     
       10. The method as recited in  claim 8 , further comprising performing, by the circuitry, a bootup operation using boot firmware stored in the persistent on-chip memory. 
     
     
       11. The method as recited in  claim 10 , further comprising:
 retrieving, by the circuitry, the boot firmware from an off-chip memory; 
 storing, by the circuitry, a copy of the boot firmware in the persistent on-chip memory; and 
 updating, by the circuitry, a flag to indicate that the persistent on-chip memory stores valid information. 
 
     
     
       12. The method as recited in  claim 8 , further comprising:
 retrieving, by the circuitry, data including the configuration information from an off-chip memory; and 
 storing, by the circuitry, a first subset of the data in the persistent on-chip memory. 
 
     
     
       13. The method as recited in  claim 8 , wherein responsive to a second condition that indicates an update procedure, the method further comprises invalidating, by the circuitry, contents of a persistent on-chip memory. 
     
     
       14. The method as recited in  claim 8 , further comprising turning off, by the circuitry, a power supply reference level used by the persistent on-chip memory, responsive to a threshold amount of time has elapsed since a most recent sleep state has begun. 
     
     
       15. A computing system comprising:
 persistent on-chip memory configured to store data; and 
 a security processor comprising: 
 circuitry, wherein responsive to a first condition that indicates initialization of at least a first client of a plurality of clients of an integrated circuit, the circuitry is configured to:
 initialize the first client using configuration information stored in a persistent on-chip memory that is accessible by the circuitry and inaccessible by the plurality of clients, responsive to an indication that the persistent on-chip memory stores valid information. 
 
 
     
     
       16. The computing system as recited in  claim 15 , wherein the first condition comprises an indication of a transition of the integrated circuit from a sleep state to an active state. 
     
     
       17. The computing system as recited in  claim 15 , wherein the circuitry is further configured to perform a bootup operation using boot firmware stored in the persistent on-chip memory. 
     
     
       18. The computing system as recited in  claim 17 , wherein the circuitry is further configured to:
 retrieve the boot firmware from an off-chip memory; 
 store a copy of the boot firmware in the persistent on-chip memory; and 
 update a flag to indicate that the persistent on-chip memory stores valid information. 
 
     
     
       19. The computing system as recited in  claim 15 , wherein the circuitry is further configured to:
 retrieve data including the configuration information from an off-chip memory; and 
 store a first subset of the data in the persistent on-chip memory. 
 
     
     
       20. The computing system as recited in  claim 15 , wherein responsive to a second condition that indicates an update procedure, the circuitry is further configured to invalidate contents of a persistent on-chip memory.